Israel's prime minister has called off a planned visit to the White House on Tuesday to deal with a crisis over a brutal naval raid that killed at least 10 pro-Palestinian activists. Netanyahu, who is in Canada, was expected to travel to Washington to meet with President Barack Obama on Tuesday. But his office said the Israeli leader decided to return home early after Monday's commando raid.

Earlier, the White House said in a written statement that the United States "deeply regrets" the loss of life and injuries and was working to understand the circumstances surrounding this "tragedy."

The commandos intercepted a flotilla of activists trying to deliver aid to the Gaza Strip.

On its part, Israel said its commandos were attacked by knives, clubs and live fire from two pistols wrested from troops after they rappelled from a helicopter to board one of the vessels.

An Israeli commando who spoke to reporters on a naval vessel off the coast said he and his comrades were surprised by a group of Arabic-speaking men when they rapelled onto the deck. He said some of the soldiers, taken off guard, were stripped of their helmets and equipment and thrown from the top deck to the lower deck, and that some had even jumped overboard to save themselves. At one point one of the passengers seized one of the soldiers' weapons and opened fire.

Turkey's NTV showed activists beating one Israeli soldier with sticks as he rappelled from a helicopter onto one of the boats.